Masahiko Tani1, Osamu Morikawa2, Shuji Matsuura3 and Masanori Hangyo1
1 Terahertz Science Group, Institute of Laser Engineering, Osaka University, 3F, 21st Century Plaza, 2-6 Yamadaoka, Suita, Osaka565-0871, Japan
2 Japan Coast Guard Academy, 5-1 Wakaba-cho, Kure, Hiroshima 737-8512, Japan
3 Department of Infrared and Sub-mm Astrophysics, Institute of Space and Astronautical Science (ISAS), Japan Aerospace Exploration Agency (JAXA), 3-1-1 Yoshinodai, Sagamihara, Kanagawa 229-8510, Japan
2 Japan Coast Guard Academy, 5-1 Wakaba-cho, Kure, Hiroshima 737-8512, Japan
3 Department of Infrared and Sub-mm Astrophysics, Institute of Space and Astronautical Science (ISAS), Japan Aerospace Exploration Agency (JAXA), 3-1-1 Yoshinodai, Sagamihara, Kanagawa 229-8510, Japan
Photomixing with dual-mode and multi-mode lasers in the sub-terahertz frequency region is presented with a description on the principle and efficiency of photomixing on low-temperature-grown-GaAs photoconductive antennae for generation of continuous-wave terahertz (THz) radiation. The difference frequency stabilization by the common-mode-rejection effect in the dual-mode lasers is discussed with several reported experimental results. It is also shown that generation and detection of broadband sub-THz radiation is possible by photomixing with multi-mode semiconductor lasers on the emitter and detector photoconductive antennae (multi-mode-laser-diode-based terahertz time-domain spectroscopy, MLD-TDS). The MLD-TDS system can be a low-cost and broadband spectrometer in the sub-THz frequency region, which is useful for measurement of complex refractive indices and carrier densities of semiconductor wafers.
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